PRB: Device Installation Conflict -- In Use by Unknown Device

Last reviewed: April 7, 1997
Article ID: Q163362

4.00 WINDOWS kbprg kbprb

The information in this article applies to:

Microsoft Win32 Device Development Kit (DDK) for Windows 95, version 4.0

SYMPTOMS

When you install a device on Windows 95, the installation may fail because of a resource conflict indicating that the I/O region is "In use by unknown device."

CAUSE

Windows 95 traps I/O accesses from ring3 code. If an I/O access occurs for an address that is not associated with any previously installed device, Windows 95 marks this I/O region as "In use by unknown device" in Device Manager.

You may cause this problem if you have ring3 code that accesses your device prior to actually installing the device (such as for detection purposes).

RESOLUTION

If you need to access your device prior to installation you can avoid having the I/O accesses trapped by performing them from a VxD.

KBCategory: kbprg kbprb
KBSubcategory:
Additional reference words: 4.00
Keywords : kbprg NTDDKKMode
Version : 4.0
Platform : WINDOWS
Issue type : kbprb

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Last reviewed: April 7, 1997
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